1. Field of the Invention
The present invention relates in general to a digital mobile communication system employing a code division multiple access (referred to hereinafter as CDMA) manner, and more particularly to a method of bypassing vocoders in the digital mobile communication system, in which a CDMA controller bypasses a voice signal without encoding and decoding it for communication between mobile stations, so that the voice quality can be enhanced.
2. Description of the Prior Art
Generally, for a mobile to LAND communication, a CDMA controller receives encoded voice data from a mobile station and decodes the received data. Then, the CDMA controller modulates the decoded data using a pulse code modulation (referred to hereinafter as PCM) manner and transmits the resultant PCM data to a switching system.
On the other hand, for a mobile to mobile communication, a CDMA controller of one mobile station receives PCM data from the other mobile station and encodes the received PCM data. Then, the CDMA controller transmits the encoded data to the corresponding mobile station.
As seen from the above description, the CDMA controller performs the unnecessary decoding and encoding operations.
However, now, the CDMA controller must perform the decoding and encoding operations for all communication processes. The decoding and encoding operations may not be necessary to some communication processes. In this case, if the decoding and encoding operations are performed, they result in an increase in delay time and a degradation in voice quality.
Therefore, the present invention has been made in view of the above problem, and it is an object of the present invention to provide a method of bypassing vocoders in a digital mobile communication system, in which the vocoders do not perform encoding and decoding operations when a communication line does not require the encoding and decoding operations, so that the voice quality can be enhanced and the delay time can be reduced.
The present invention is directed to a method of bypassing vocoders in Mobile-to-Mobile Call (MMC). In the call establishment process of a digital mobile communication system, the Mobile Service Switching Center (MSC) usually decides if a call is a Mobile-to-Mobile call or a Mobile-to-Land call. This operation of MSC is known in the art.
In accordance with the present invention, the above and other objects can be accomplished by a provision of a method of bypassing vocoders in a digital mobile communication system, comprising the step of appending bypass mode data to data transmitted from a plurality of mobile stations, the bypass mode data instructing the vocoders not to perform encoding/decoding operations, and the step of transmitting the resultant data.